Circuitry and techniques for determining swelling of a battery/cell and adaptive charging circuitry and techniques based thereon

ABSTRACT

Disclosed are methods and systems for measuring and managing swelling of rechargeable batteries in situ. Some implementations involve using capacity fade or state of health of rechargeable batteries to estimate swelling of the rechargeable batteries. Some implementations provide methods and systems for measuring battery swelling based on inductive or capacitive coupling between sensors and the battery. Some implementations provide means to manage or reduce swelling of rechargeable batteries by applying adaptive charging with consideration of battery swelling.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims benefits under 35 U.S.C. §119(e) to U.S.Provisional Patent Application No. 62/068,345, entitled: CIRCUITRY ANDTECHNIQUES FOR DETERMINING SWELLING OF A BATTERY/CELL AND ADAPTIVECHARGING CIRCUITRY AND TECHNIQUES BASED THEREON, filed Oct. 24, 2014,which is herein incorporated by reference in its entirety for allpurposes.

TECHNICAL FIELD

This disclosure relates to technology for measuring and managing batteryswelling. In particular, some embodiments provide methods and systemsfor estimating battery swelling based on capacity fade or state ofhealth of rechargeable batteries. Other embodiments involve measuringbattery swelling using capacitive or inductive sensors. Systems andmethods for managing battery swelling by adaptive charging are alsoprovided.

DESCRIPTION OF THE RELATED TECHNOLOGY

Batteries are widely used in many consumer electronics and otherapplications such as electric cars and electronic instruments. For manyapplications, swelling of the batteries can cause problems, becausethese applications require small and thin products (e.g., in cellphones) or a large number of batteries assembled in a tight space (e.g.,in electric cars). A battery can take up the majority of one or morephysical dimensions of a cell phone, for example. If the battery swellsduring its life, which is common with battery technologies, the phonemay break or become functionally/structurally compromised if there isnot enough extra space to accommodate the swelling. For example, if themobile device manufacturers make a larger or thicker mobile device toaccommodate the swelling of the battery, such a device has lessdesirable consumer specifications. Therefore, it is desirable to monitorand manage battery swelling in these applications. This disclosureprovides methods, systems, and products for monitoring or managingbattery swelling that may be implemented in various applications.

SUMMARY

In some embodiments, methods and apparatus are provided for estimatingswelling in a battery by determining capacity face and/or state ofhealth. In some embodiments, methods and apparatus are provided usinginformation about battery swelling to adapt a charging process to, forexample, reduce swelling or future increases in swelling.

One aspect of the disclosure relates to methods for estimating swellingof a rechargeable battery. In some implementations, the method involves:determining capacity fade of the rechargeable battery in use; andestimating swelling of the rechargeable battery using the determinedcapacity fade of the rechargeable battery.

In some implementations, estimating the swelling involves applying arelationship for predicting battery swelling from battery capacity fade.In some implementations, the method further involves: storing therelationship in a memory; and retrieving the relationship from memoryfor estimating the swelling. In some implementations, the relationshipwas obtained by: (i) charging and discharging one or more samplerechargeable batteries for one or more charge cycles; (ii) measuringcapacity fade of the one or more sample rechargeable batteries; (iii)measuring swelling of the one or more sample rechargeable batteries;(iv) repeating (i)-(iii) one or more times, thereby obtaining two ormore data points corresponding to capacity fade and swelling in two ormore charge cycles for the one or more sample rechargeable batteries;and (v) forming the relationship for predicting battery swelling frombattery capacity fade using the two or more data points. In someimplementations, determining capacity fade of a rechargeable batteryinvolves determining capacity fade in two or more charge cycles.

In some implementations, the method further involves adjusting acharging sequence for the rechargeable battery based at least in part onthe estimated swelling of the rechargeable battery.

In some implementations, adjusting the charging sequence reduces theestimated swelling of the rechargeable battery. In some implementations,adjusting the charging sequence may involve operations such as: reducingan amplitude of a charge pulse, terminating the charging sequence,reducing the pulse width, applying one or more negative pulses,increasing an amplitude of a negative pulse, increasing a width of anegative pulse, increasing a duration of a rest period, and changing atiming of a rest period. In some implementations, adjusting the chargingsequence involves adjusting one or more aspects of the charging sequenceinvolves adjusting one or more aspects of a charge or discharge pulseselected from the group consisting of: a shape of the pulse, anamplitude of the pulse, a duration of the pulse, a duty cycle a sequenceof pulses, and a rest period between the pulses. In someimplementations, adjusting the charging sequence involves adjusting oneor more characteristics of a charging signal of a constant-current,constant-voltage (CCCV) charging technique or a step charging technique.In some implementations, adjusting the charging sequence involvesadjusting an amplitude of a charge current or a number of steps ofcharge current.

In some implementations, adjusting the charging sequence involves:determining that the swelling of the battery exceeds a predeterminedrange or value and performing one or more of the following operations:reducing an amplitude of a charge current, terminating the chargingsequence, increasing a number of charge steps over a charge period,adjusting a step width of one or more charge steps, introducing one ormore negative pulses, or adjusting an amplitude or pulse width of one ormore negative pulses. In some implementations, adjusting the chargingsequence involves terminating a charging sequence when the SOC of thebattery reaches 85% or lower of a previous or initial SOC of thebattery. In some implementations, adjusting the charging sequence is atleast partially based on one or more of the following parameters: anover-potential (OP) of the battery, a full relaxation time (FRT) of thebattery, a charge pulse voltage (CPV), a change in CPV, a partialrelaxation time (PRT) of the battery, a temperature of the battery/cell(T° b/c), a temperature of the charging circuitry (T° cc), a temperatureof the housing (T° h), a maximum current applied to the battery duringcharging operations (Imax), and a maximum terminal voltage duringcharging operations (Vmax).

Another aspect of the disclosure relates to a method for determining arelationship for predicting swelling of batteries from capacity fade ofthe batteries. The method involves: (a) charging and discharging one ormore rechargeable batteries for one or more charge cycles; (b) measuringcapacity fade of the one or more rechargeable batteries; (c) measuringswelling of the one or more rechargeable batteries; (d) repeating(a)-(c) one or more times, thereby obtaining two or more data pointscorresponding to capacity fade and swelling in two or more charge cyclesfor the one or more rechargeable batteries; (e) determining therelationship for predicting battery swelling from battery capacity fadeusing the two or more data points; and (f) storing data describing therelationship in a memory. In some implementations, the relationshipincludes a mathematical relationship between the capacity fade andswelling. In some implementations, determining a relationship involvesfitting the mathematical relationship to the two or more data points. Insome implementations, the relationship includes a look-up table. In someimplementations, the one or more rechargeable batteries include two ormore rechargeable batteries, and wherein determining a relationshipincludes averaging data points from the two or more rechargeablebatteries to obtain averaged data.

An additional aspect of the disclosure relates to another system forestimating swelling of a rechargeable battery, the system involves: (a)a charging circuitry configured to apply a charging sequence for therechargeable battery; (b) a measurement circuitry configured to measurevoltage or charge passing at terminals of the rechargeable battery; and(c) logic configured to: determine capacity fade of the rechargeablebattery in use, wherein the logic determines capacity fade usingmeasured voltage and/or charge from the measurement circuitry; andestimate swelling of the rechargeable battery using the determinedcapacity fade of the rechargeable battery. In some implementations,estimating the swelling involves applying the determined capacity fadeto a relationship for predicting battery swelling from battery capacityfade. In some implementations, the logic is further configured to adjustthe charging sequence, applied by the charging circuitry, based at leastin part on the estimated swelling of the rechargeable battery.

A further aspect of the disclosure relates to a system for estimatingswelling of batteries. The system includes one or more inductive orcapacitive sensors disposed proximate to a surface of a battery orintegrated in or on a non-metallic surface above a metallic component ofthe battery. The system also includes an electronic circuitry configuredto obtain proximity data indicating a change of inductive and/orcapacitive coupling between the one or more sensors and said surface orsaid metallic component; and calculate a displacement of said surface orsaid metallic component from the proximity data, thereby estimateswelling of the battery. In some implementations, the one or moresensors include one or more inductive sensors that each includes a coilto carry a current to induce eddy currents to generate an eddy-currentmagnetic field. In some implementations, the coil is incorporated aspart of a resonator. In some implementations, the one or more inductivesensors include one or more parallel capacitors. In someimplementations, the system further includes a sensor target element onor in an external surface of the battery proximate to the one or moresensors. In some implementations, the electronic circuitry is configuredto apply an averaging function, a minimum function, or a maximumfunction to the proximity data. In some implementations, the electroniccircuitry is configured to apply corrections to the proximity data basedon temperature, charge time, charge current, charge voltage, state ofcharge, or state of health. In some implementations, the system furtherincludes an array of multiplexers, wherein the one or more sensorsinclude a plurality of sensors, and wherein the system wherein theelectronic circuit is further configured to control the multiplexers tomanage which sensors are used.

A related aspect of the disclosure relates to a method for estimatingswelling of a rechargeable battery. The method involves: measuring achange of inductance or capacitance between one or more inductive orcapacitive sensors and a surface of the battery or a metallic componentof the battery; calculating a displacement of said surface or saidmetallic component from the change of inductance or capacitance, andestimating swelling of the battery from the displacement.

Yet another aspect of the disclosure relates to a method for determininga relationship for predicting swelling of batteries from a state ofhealth (SOH) of the batteries. The method involves: (a) charging anddischarging one or more rechargeable batteries for one or more chargecycles; (b) measuring values of the SOH of the one or more rechargeablebatteries; (c) measuring swelling of the one or more rechargeablebatteries; (d) repeating (a)-(c) one or more times, thereby obtainingtwo or more data points corresponding to the SOH and swelling in two ormore charge cycles for the one or more rechargeable batteries; (e)determining the relationship for predicting battery swelling from theSOH using the two or more data points; and (f) storing data describingthe relationship in a memory. In some implementations, the SOH isrepresentative of degradation of the battery and/or an ability of thebattery to hold a charge. In some implementations, measuring values ofthe SOH involves measuring terminal voltages or values derived therefromfor the one or more rechargeable batteries. In some implementations, therelationship for predicting battery swelling from the SOH includes amathematical relationship between the SOH and swelling. The mathematicalrelationship between the SOH and swelling may include a mathematicalrelationship between the SOH and capacity fade and a mathematicalrelationship between the capacity fade and swelling.

These and other features of the disclosure will be presented in moredetail below with reference to the associated drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosures may be implemented in connection withimplementations illustrated in the attached drawings. These drawingsshow different aspects of the present disclosures and, whereappropriate, reference numerals illustrating like structures,components, materials and/or elements in different figures are labeledsimilarly. It is understood that various combinations of the structures,components, and/or elements, other than those specifically shown, arecontemplated and are within the scope of the present disclosures.

Moreover, there are many disclosures described and illustrated herein.The present disclosures are neither limited to any single aspect norimplementation thereof, nor to any combinations or permutations of suchaspects or implementations. Moreover, each of the aspects of the presentdisclosures, and/or implementations thereof, may be employed alone or incombination with one or more of the other aspects of the presentdisclosures and/or implementations thereof. For the sake of brevity,certain permutations and combinations are not discussed or illustratedseparately herein. Notably, an implementation described herein as“exemplary” is not to be construed as preferred or advantageous, forexample, over other implementations; rather, it is intended reflect orindicate the implementation(s) is/are “example” implementation(s).

FIG. 1 is a functional illustration of a conventional lithium-ionbattery or cell including an anode (negative electrode) and a cathode(positive electrode) and conductive electrolyte (for example, a mixtureof carbonates and lithium salt);

FIGS. 2A and 2B illustrate block diagram representations of exemplarysystems for, among other things, estimating changes in thickness orlength (i.e., swelling) of a battery/cell (for example, a lithium-ionbattery/cell) for example, in situ, during or in use, and/or whenundergoing charging or recharging, according to at least certain aspectsof certain implementations of the present disclosures, wherein theestimating may be performed in situ, in use, and duringcharging/recharging, while FIG. 2B includes charging circuitry, controlcircuitry and monitoring circuitry which may, in addition, be employedto adaptively charge a battery/cell based on or using data that isrepresentative of swelling; notably, although the system is illustratedas including charging circuitry, control circuitry and monitoringcircuitry, in one implementation, the system may include only chargingcircuitry and in another implementation, the system may include chargingand control/processing circuitry;

FIG. 3 is a graphical illustration of an exemplary relationship ofswelling of the battery/cell as a function of capacity retention(plotted with decreasing retention along the x-axis) according to atleast certain aspects of certain implementations of the presentdisclosures, wherein the swelling of the battery/cell increases as thecapacity of the battery/cell decreases over time, use, or charge cycles;notably, the amount of swell may depend on the technique employed tocharge or recharge the battery (for example, an adaptive chargingtechnique versus non-adaptive CCCV charging technique), in addition tocapacity retention;

FIG. 4 is a graphical illustration of the maximum swelling of abattery/cell as a function of the number of cycles achieved before thecell's capacity reached 80% of the initial capacity; notably, whenimplementing an adaptive charging technique, the cycle life of thebattery/cell is extended (relative to a CCCV charging technique) bymitigating the degradation mechanisms taking place while the cells wereconstantly charging and discharging; as evident, the type of chargingsequence employed may have an impact on the amount of swelling of thebattery/cell as a function of cycle number (FIG. 4), and a relativelyminor effect on the amount of swelling as a function of capacityretention (FIG. 3), as indicated by the separation between the curvesfor conventional CCCV and adaptive charging sequences;

FIG. 5 is an exemplary block diagram representation of a configurationto measure, determine and/or detect swelling according to at leastcertain aspects of certain implementations of the present disclosures,wherein the cell thickness is measured using a thickness gaugemeasurement device (for example, Mitutoyo Digimatic Indicator (ModelNumber 543)); in one exemplary implementation, the thickness gaugemeasurement device may be mounted on an SPI comparator with a givenresolution (for example, one micron) and exerts a measuring force ofless than 1.5N; notably, features in FIG. 5 are not drawn to scale: thedimensions of some features may be exaggerated relative to otherelements to improve understanding of the exemplary implementations; forexample, one of ordinary skill in the art appreciates that themeasurement locations are not drawn to scale and should not be viewed asrepresenting proportional relationships relative to the external surfaceof the battery/cell;

FIGS. 6A and 6B are exemplary block diagram representations ofnon-contact configurations to measure, determine and/or detect swellingaccording to at least certain aspects of certain implementations of thepresent disclosures, wherein the cell thickness is measured usinginductive sensing (FIG. 6A) or capacitive sensing (FIG. 6B);

FIGS. 6C and 6D are exemplary block diagram representations ofnon-contact configurations to measure, determine and/or detect swellingaccording to at least certain aspects of certain implementations of thepresent disclosures, wherein the cell thickness is measured using aninductive and/or capacitive sensing technique to detect a thickness orchange in thickness (or rate of change) of the battery/cell wherein theinductive and/or capacitive sensors are disposed or located proximate toan external surface of the battery/cell (FIG. 6C), or in or on anexternal surface of the battery/cell (FIG. 6D) when, for example, theexternal surface of the battery/cell is non-metallic; electroniccircuitry measures the change in inductive/capacitive coupling betweenone or more sensors and the surface of the battery/cell to measure thedisplacement of the surface (and consequently, swelling of the battery);the sensors may be implemented as coils or plates, and they may beconfigured to have a planar form in some implementations; notably,similar to FIG. 5, features in FIGS. 6C and 6D are not drawn to scale:the dimensions of some features may be exaggerated relative to otherelements to improve understanding of the exemplary implementations; forexample, one of ordinary skill in the art appreciates that themeasurement locations are not drawn to scale and should not be viewed asrepresenting proportional relationships relative to the external surfaceof the battery/cell;

FIG. 7 plots a voltage-charge curve of a lithium-ion battery/cell as thebattery/cell ages, deteriorates and/or degrades; here, thevoltage-charge curve shifts leftward as charge cycle increases, showingdegrading SOH of the battery indicated by increasing charge voltagesrequired to achieve the same charge capacity when charge cycleincreases;

FIGS. 8A-8C illustrate exemplary block diagram representations ofexemplary adaptive charging circuitry in conjunction with abattery/cell, according to at least certain aspects of certainimplementations of the present disclosures, wherein the controlcircuitry may employ swelling-related data (alone or in conjunction withone or more other considerations, parameters, constraints and/orrequirements) to change, adjust, control and/or vary the chargingcurrent signal(s), including the characteristics thereof; notably, thecontrol circuitry may also receive current, voltage and temperature data(for example, feedback data) from the monitoring circuitry (notillustrated) and, in response thereto, evaluate, analyze and/ordetermine the conditions of the battery and/or charging circuitry duringthe charge sequence, cycle or operation of the battery/cell;

FIGS. 9A-9D illustrate exemplary waveforms illustrating a plurality ofexemplary charging signals and discharging signals of an exemplarycharging technique, wherein such charging signals may generally decreaseaccording to a predetermined rate and/or pattern (for example,asymptotically, linearly or non-linearly (for example, quadratically))as the terminal voltage of the battery/cell increases during a chargingor recharging sequence, operation or cycle (see, FIGS. 9B and 9D);notably, a charging sequence, operation or cycle may include chargingsignals (which, in total, inject or apply charge into the battery/cell)and discharging signals (which, in total, remove charge from thebattery/cell); moreover, a pulse charging sequence or operation mayinclude a constant voltage (CV) phase after a period of pulse chargingand/or upon charging the battery/cell to a predetermined state ofcharge;

FIGS. 10A-10N illustrate exemplary charge and/or discharge packets ofthe charging and discharging signals (which are exemplary illustrated inFIGS. 10A-10D), wherein such charge and discharge packets may includeone or more charge pulses and one or more discharge pulses; notably, inone implementation, each charge signal of FIGS. 9A-9D may include aplurality of packets (for example, about 100 to about 50,000 packets)and, in one implementation, each packet may include a plurality ofcharge pulses, discharge pulses and rest periods; notably, the pulsesmay be any shape (for example, rectangular, triangle, sinusoidal orsquare); in one exemplary implementation, the charge and/or dischargepulses of the packet may include a temporal duration of between about 1ms to about 2000 ms, and preferably less than 1000 ms; moreover, asdiscussed in detail below, one, some or all of the characteristics ofthe charge and discharge pulses (for example, pulse amplitude, pulsewidth/duration and pulse shape) are programmable and/or controllable viacharging circuitry wherein the amplitude of the positive and/or negativepulses may vary within the packet (and are programmable and/orcontrollable), the duration and/or timing of the rest periods may varywithin the packet (and are programmable and/or controllable) and/or, inaddition, such pulses may be equally or unequally spaced within thepacket; the combination of charging pulses, discharging pulses and restperiods may be repetitive and thereby forms a packet that may berepeated; all combinations or permutations of pulse, pulsecharacteristics, periods, packets and signal characteristics andconfigurations are intended to fall within the scope of the presentdisclosures; notably, such one or more charge pulses and/or one or moredischarge pulses (including, for example, pulses of charge and/ordischarge packets) may be generated via the controllable switch(es) ofthe charging circuitry;

FIG. 100 illustrates an exemplary charge packet having a charge pulseincluding a charging period (Tcharge) followed by a rest period (Trest)wherein the period of the charge packet is identified as Tpacket,according to certain aspects of the present disclosures;

FIG. 10P illustrates an exemplary charge packet having a charge pulse(which injects charge into the battery/cell) and a discharge pulse(which removes charge from the battery/cell) wherein the charge pulseincludes a charging period (Tcharge) and the discharge pulse includes adischarging period (Tdischarge), according to certain aspects of thepresent disclosures; notably, in this exemplary charge packet, anintermediate rest period (Tinter) is disposed between the charge anddischarge pulses, and a rest period (Trest) is disposed after thedischarge pulse and before the next packet; notably, one, some or all ofthe characteristics of the charge pulses (for example, pulse amplitude,pulse width/duration and pulse shape) are programmable and/orcontrollable via charging circuitry wherein the amplitude of thepositive and/or negative pulses may vary within the packet (and areprogrammable and/or controllable), the duration and/or timing of therest periods may vary within the packet (and are programmable and/orcontrollable) and/or, in addition, such pulses may be equally orunequally spaced within the packet; the combination of charging pulses,discharging pulses and rest periods may be repetitive and thereby formsa packet that may be repeated; all combination or permutations of pulse,pulse characteristics, periods, packets and signal characteristics andconfigurations are intended to fall within the scope of the presentdisclosures; moreover, discharge packets may have similarcharacteristics as charge packets except, however, a net charge isremoved from the battery/cell; for the sake of brevity, thediscussion/illustration with respect to discharge packet will not berepeated;

FIG. 11A illustrates current and voltage of a battery/cell as a functionof time illustrating the conventional charging method known asconstant-current, constant-voltage (CCCV); notably, a conventionalmethod to charge a rechargeable battery, including a lithium-ion typerechargeable battery, employs a CCCV technique, wherein the chargingsequence includes a constant-current (CC) charging mode until theterminal voltage of the battery/cell is at about a maximum amplitude(for example, about 4.2V to 4.5V for certain lithium-ion typerechargeable batteries) at which point the charging sequence changesfrom the constant-current charging mode to a constant-voltage (CV)charging mode, wherein in the CV mode, a constant voltage is applied tothe terminals of the battery/cell until a termination current is reached(for example, a current in the range of about 0.02 C to 0.05 C); in theCCCV technique, the charging circuitry often changes from the CCcharging mode to the CV charging mode when the state of charge (SOC) ofthe battery/cell is at about 50-80%, depending on the applied current(notably, at higher currents, the transition to CV may be less than 50%SOC;

FIG. 11B illustrates current and voltage of a battery/cell as a functionof time illustrating a charging method known as step-charging; notably,a method to step-charging a rechargeable battery, including alithium-ion type rechargeable battery, employs a multiple step chargingmode where the current is decreased at different voltages until thelower current reaches a terminal voltage of the battery/cell at about amaximum amplitude (for example, about 4.2V to 4.5V for certainlithium-ion type rechargeable batteries) at which point the chargingsequence changes from the constant-current charging mode to aconstant-voltage (CV) charging mode, wherein in the CV mode, a constantvoltage is applied to the terminals of the battery/cell; and

FIGS. 12A-12C illustrate block diagram representations of exemplaryadaptive charging circuitry in conjunction with a battery/cell,according to at least certain aspects of certain implementations of thepresent disclosures, wherein FIG. 12B includes discrete memory coupledto the control circuitry, and FIG. 12C illustrates circuitry externalwhich accesses the memory to store data (for example, one or morepredetermined ranges) employed by control circuitry in conjunction withadapting, adjusting and/or controlling one or more characteristics ofthe charge or current applied to or injected into the battery/cell inaccordance with or based on the thickness or change in thickness (orrate of change) of the battery/cell.

Again, there are many disclosures described and illustrated herein. Thepresent disclosures are neither limited to any single aspect norimplementation thereof, nor to any combinations and/or permutations ofsuch aspects and/or implementations. Each of the aspects of the presentdisclosures, and/or implementations thereof, may be employed alone or incombination with one or more of the other aspects of the presentdisclosures and/or implementations thereof. For the sake of brevity,many of those combinations and permutations are not discussed separatelyherein.

DETAILED DESCRIPTION

The disclosed implementations concern methods, apparatus, and systemsfor estimating, calculating, measuring and/or determining the thicknessor changes in thickness of a battery.

The term “battery” as used herein refers to one or more galvanic cellsunless specified otherwise. Although some technical materials describe abattery as including two or more cells, the term “battery” is not solimited in this disclosure. In some implementations, a battery can be asingle cell or multiple cells connected together in series or parallelto make the desired voltage or current rating.

A “charge cycle” is the process of charging a rechargeable battery anddischarging it with a particular load. In some implementations, a chargecycle means charging and discharging a load equivalent to the battery'scapacity, but not necessarily by one full charge and one full discharge.For instance, using half the charge of a fully charged battery,recharging it, and then using the same amount of charge again count asone charge cycle. The number of charge cycles to failure indicates howmany times a rechargeable battery can undergo the process of completecharging and discharging until failing certain criteria. The number ofcharge cycles may be used to specify a battery's expected life, whichmay affect battery life more than the mere passage of time.

“Measuring” an attribute as stated herein is a way of obtaining a valueof the attribute. For instance, measuring the voltage of a battery canmean using an instrument such as a voltmeter to directly measure thevoltage between terminals of the battery. In some context, it may alsomean obtaining data related to the voltage of the battery (e.g.,capacity fade of a battery) and/or deriving other information about thebattery (e.g., battery swelling). Typical measurements of a battery mayinclude current, charge passed or coulombs injected into the battery,voltage, size, and temperature.

The term “capacity fade” refers to reduction of battery capacity overtime or charge/discharge cycles. It may be based on a maximum of thebattery capacity or other reference values of battery capacity (e.g.,85% of initial maximum capacity, capacity at specific terminal voltage,etc.)

State of charge (SOC) may refer to the present battery capacity as apercentage of maximum capacity. SOC may be calculated using currentintegration to determine the change in battery capacity over time orcharge/discharge cycles.

Terminal voltage is the voltage between the battery terminals with loadapplied. Terminal voltage may vary with SOC and discharge/chargecurrent.

Capacity or nominal capacity in implementations refers to thecoulometric capacity, e.g., the total Amp-hours available when thebattery is discharged at a certain discharge current (which may bespecified as a C-rate) from 100 percent state-of-charge to a definedcut-off voltage.

The term “swelling” refers to an increase in the size, volume, or anydimensions of the battery.

Determining a “relationship” as used herein refers to determining arelationship between one or more input variables and one or more outputvariables. In some implementations, the relationship includes amathematical function relating one or more input variables to an outputvariable. In some implementations, the relationship includes aunivariate or a multi-variate model using one or more input variables topredict one or more output variables. In other implementations, therelationship may be implemented as a lookup table containing values forone or more input variables and corresponding values for one or moreoutput variables. The relationship may be simply a correlation betweenthe one or more input variables and one or more output variables.

The state of health (SOH) of a battery (for example, a rechargeablelithium-ion (Li+) battery, is a parameter that describes, characterizes,or is representative of the “age” of the battery and/or ability of thebattery to hold charge, for example, relative to a given time inoperation (for example, the initial time in operation). The SOH of abattery provides information to estimate, calculate, measure, and/ordetermine other battery parameters such as the ability of a battery tohold a charge. The voltage at the terminals of the battery changes asthe SOH changes—and, hence the voltage curves of the battery shift as itages and its SOH deteriorates.

Numeric ranges are inclusive of the numbers defining the range. It isintended that every maximum numerical limitation given throughout thisspecification includes every lower numerical limitation, as if suchlower numerical limitations were expressly written herein. Every minimumnumerical limitation given throughout this specification will includeevery higher numerical limitation, as if such higher numericallimitations were expressly written herein. Every numerical range giventhroughout this specification will include every narrower numericalrange that falls within such broader numerical range, as if suchnarrower numerical ranges were all expressly written herein.

The headings provided herein are not intended to limit the disclosure.

Unless defined otherwise herein, all technical and scientific terms usedherein have the same meaning as commonly understood by one of ordinaryskill in the art. Various scientific dictionaries that include the termsincluded herein are well known and available to those in the art.Although any methods and materials similar or equivalent to thosedescribed herein find use in the practice or testing of theimplementations disclosed herein, some methods and materials aredescribed.

As used herein, the singular terms “a,” “an,” and “the” include theplural reference unless the context clearly indicates otherwise.

The logical connector “or” as used herein is inclusive unless specifiedotherwise. As such, condition “A or B” is satisfied by “A and B” unlessspecified otherwise.

INTRODUCTION

Because battery swelling may functionally or structurally compromisebattery-powered devices, it is desirable to monitor and manage batteryswelling in various applications. Conventional instrumentation such asmechanical or electronic calipers and indicators can be used to measuredimensions of batteries, but are not suitable for monitoring batteries,e.g., rechargeable batteries, in situ when the batteries are being used,charged, and discharged in consumer electronics and other usedscenarios. Some implementations of the current disclosure providemethods and systems for estimating battery swelling in situ whenconventional instrumentations and methods are unsuitable. Some of theseimplementations can estimate swelling from data collected bypre-existing components of the battery-powered devices. Someimplementations can measure swelling using sensors disposed proximate toor on the batteries.

In addition to monitoring swelling of batteries, another aspect of thedisclosure provides methods and systems for reducing or managing batteryswelling, which may improve battery life, safety, form factor, orfunctions of battery-powered devices. Some implementations achieve theseimprovements through adaptive charging based on data related to batteryswelling.

The present disclosures, in certain aspects, are directed to circuitryand techniques for estimating thickness or changes in thickness (i.e.,swelling) of a battery (for example, a lithium-ion battery) for example,in situ, during or in use, and/or when undergoing charging or recharging(hereinafter collectively “charging”). Estimation or estimating is aprocess of finding an estimate, or approximation, of a quantity orquality of interest, which is useful regardless if input data isincomplete, uncertain, or unstable. In some applications, estimation mayinvolve using the value of a statistic derived from one or more samples(e.g., terminal charge of a number of test batteries) to estimate thevalue of a corresponding population parameter (e.g., thickness ofbatteries of the instant kind). In some implementations, “estimating” aquantity comprises operations for measuring, calculating, evaluating,and/or determining the quantity.

In one exemplary implementation, swelling of a battery is estimatedbased on a value of or derived from a capacity of the battery (forexample, the amount of capacity during use, operation and charging orrecharging). In some implementations, the value of or derived fromcapacity may be a change, fade, loss, or reduction of capacity over timein various implementations. In some implementations, the value may beother measures derived from capacity, such as rate of change ofcapacity, inflection or asymptote of a mathematical function involvingcapacity or capacity fade. The capacity, or change in capacity of thebattery may be estimated using any technique or circuitry now known orlater developed. For example, the fade of capacity may be estimatedusing a state of health (SOH) measure of the battery or using a chargevoltage to charge capacity relationship. For example, in the chargevoltage to charge capacity relationships shown hereinafter, the chargevoltage changes across charging cycles, indicating a higher voltagevalue for the same amount of charge stored within the battery acrosscharging cycles, the increase of charge voltage indicating a capacityfade of the battery.

In another exemplary implementation, battery swelling is estimated basedon a SOH of the battery. Notably, the SOH of a rechargeable battery (forexample, a rechargeable lithium-ion battery) is a parameter thatdescribes, characterizes or is representative of the “age” of thebattery, the degradation levels of the battery or an ability of thebattery to hold charge, for example, relative to a given time inoperation (for example, the initial time in operation). The SOH of thebattery may be estimated using any technique or circuitry now known orlater developed including, for example, the techniques described orillustrated in, for example, U.S. application Ser. No. 13/366,352, U.S.application Ser. No. 13/657,841 and U.S. application Ser. No.14/003,826—all of which are incorporated herein by reference.

The present disclosures, in other aspects, are directed to circuitry andtechniques for adaptively charging a battery based on or using datawhich is representative of the thickness or change in thickness (or rateof change) of the battery. In one implementation, the adaptive chargingtechniques or circuitry uses or employs such data, alone or inconnection with other considerations, parameters, constraints orrequirements, to change, adjust, control or vary the charging currentsignal(s), including the characteristics thereof. For example, in oneexemplary implementation where the battery is charged using pulsecurrent charging techniques (see, e.g., FIGS. 9A-9D and 10A-10P), thecircuitry and techniques of the present disclosures may implement,provide, change, adjust or control one or more characteristics of thecharging signal applied to the battery (for example, a shape of chargeor discharge signal (if any), amplitude thereof, duration thereof, dutycycle thereof, rest period (if any) or sequence of charge or dischargepulses) according to the amount of swelling of the battery. Suchtechniques may facilitate managing or controlling the thickness orchange (or rate thereof) in thickness of the battery.

In addition thereto, or in lieu thereof, such techniques may facilitatemeeting or compliance with safety considerations, conditions or “goals”defined by, associated with or corresponding to the battery—for example,limit or control the thickness of the battery (or change therein) to notexceed a given amount (which may depend on the state of charge (SOC) orSOH of the battery). In one implementation, the amount of swell iscontrolled or limited by adjusting the charging signal (as indicatedabove) or reducing the maximum SOC or the charge level of the battery asa result of a full or complete charging sequence. For example, thethickness of the battery (or change in thickness of the battery) may becontrolled or managed by terminating a charging sequence when a SOC ofthe battery is less than 100% —for example, terminating the chargingsequence when the battery is charged to 90-95% of a previous SOC,battery rating or a SOC of a new battery (for example, theoriginal/initial SOC of that battery (i.e., when that battery was“new”)). In this way, the thickness or change in thickness (or ratethereof) of the battery may be managed or controlled to not exceed apredetermined range or value, for example, to reduce potentially adverseimpact or consequences of swelling.

In another implementation, the circuitry and techniques of the presentdisclosures may adaptively charge a battery to a SOC that is defined bya predetermined range or thickness value or change in thickness (or ratethereof) of the battery. In this regard, the circuitry and techniquesmay correlate capacity retention to an “acceptable” percentage ofswelling and based thereon, charge a battery to a SOC that is defined byor associated with such fade or change in, loss or reduction of acapacity of the battery. Here the “acceptable” thickness or change inthickness (or rate thereof) of the battery may be based on a number offactors including meeting or compliance with safety considerations. Inthis way, circuitry and techniques manage or control the thickness orchange in thickness (or rate thereof) of the battery to not exceed apredetermined range or value (for example, to reduce potentially adverseimpact or consequences of swelling) by correlating the fade or changein, loss or reduction of a capacity of the battery to a SOC of thebattery that maintains the thickness or change in thickness (or ratethereof) of the battery to a predetermined range or value.

Notably, the SOC of a battery, for example, a lithium-ion rechargeablebattery, is a parameter that is representative or indicates the level ofelectrical charge available in the battery. It may be characterized as apercentage of the nominal full charge rating of the battery, wherein a100% SOC indicates that a battery is fully charged and a 0% indicatesthat the battery is fully discharged. The SOC of the battery may also becharacterized as an available charge stored in the battery relative to amaximum available charge stored in the battery—wherein the maximumavailable charge may change over time as, for example, the battery agesor deteriorates.

In another exemplary implementation, where the battery is charged usinga constant-current, constant-voltage (“CCCV”) charging technique or astep charging technique (see, e.g., FIGS. 11A and 11B), the circuitryand techniques of the present disclosures may implement or adapt thecharging operation, in accordance with, using or based on the swellingdata to implement, determine, change, adjust, control or vary anamplitude of the charging current applied to or voltage of the batteryduring the charging operation. For example, the number of steps,amplitude of one or more steps, voltage of one or more steps or lengthof time of one or more steps may be adjusted according to the amount ofswelling of the battery. Further, in a CCCV technique, the transitionfrom CC to CV may be adjusted or based on the amount of swellingexperienced by the battery during, for example, the charging operation.

As noted above, such techniques may facilitate managing or controllingthe amount of swell of the battery or meeting or compliance with safetyconsiderations, conditions or “goals”—for example, limiting, managing orcontrolling the thickness of the battery (or change therein) to remainbelow or within (or not exceed) a given limit. Such given limit maydepend on the SOC or SOH of the battery. Indeed, in one implementation,the amount of swell is controlled or limited by adjusting the chargingsignal (as indicated above) or reducing the maximum SOC of the batteryas a result of a complete or full charging sequence. For example, thethickness or change in thickness of the battery may be controlled duringa charging operation by terminating a charging sequence when a SOC ofthe battery is less than 100% —for example, at 85% of a previous SOC,rating or a new battery. In this way, a thickness or change in thicknessof the battery may be managed so that such thickness does not exceed agiven amount during a charging operation.

Briefly, by way of background, with reference to FIG. 1, there are threeprimary functional components of a lithium-ion battery—including anegative electrode (anode) and a positive electrode (cathode) andelectrolyte (for example, a mixture such as mixture of organiccarbonates and lithium salt). During the charge and dischargeoperations, the electrodes of a lithium-ion battery often “breathe” orundergo changes in thickness (expand or contract) as lithium isintercalated in and de-intercalated out of the electrode. Over time,however, as the battery is repeatedly charged and discharged, theoverall thickness of the battery tends to increase. Indeed, in a polymerbattery, which employs a soft external polymer pouch for packagingversus a battery that uses a metal casing for packaging, the increasebecomes more pronounced because a polymer cell/battery is generallyunconstrained by such packaging.

Swelling due to lithium intercalation is, for the most part, reversiblefrom cycle to cycle. However, there are additional factors that impactswelling that tend to be irreversible from cycle to cycle(charging-discharging/use-charging . . . )—for example, gas generation,mechanical failure of the electrodes, manufacturing defects andoperating conditions (temperature, charge/discharge voltage,charge/discharge current). Irreversible swelling tends to result in amore permanent increase in the thickness of the battery.

A lithium-ion battery typically includes one or more metal oxidecathodes and one or more graphitic anodes. It has been observed thatduring lithium intercalation cathodes tend to swell approximately 3-4%of their original thickness while anodes swell approximately 7-10% forgraphite-based anodes. Alloy-based anodes using silicon or siliconcomposite can swell up to 300%. The amount of swelling in a battery istypically dependent on when, relative to the charge state of thebattery, thickness measurements are made. The battery is often at amaximum thickness when it is fully charged wherein when fully charged,the anode is at its maximum thickness. The battery is often at a minimumthickness when it is fully discharged wherein when fully discharged, theanode is at its minimum thickness.

The swelling or change in thickness of the battery may occurnon-uniformly or in a non-uniform pattern across the surface of thebattery. As such, the amount of swelling may be a measure of an averageincrease in thickness across the battery or a maximum increase inthickness across the surface of the battery. Notably, it may beadvantageous to measure the swell or the amount of swelling when thecell is not physically or mechanically constrained in order to determinethe maximum increase in thickness or highest point or area on thesurface of the battery.

Implementations

Estimating Battery Swelling

There are many disclosures described and illustrated herein. In oneaspect, the present disclosures are directed to circuitry and techniquesfor estimating the thickness or changes in thickness (i.e., swelling ofthe battery) of a battery. Such circuitry and techniques may estimatethe thickness or change in thickness of a battery in situ, when thebattery is in use, such as when the battery is undergoing charging. Inone exemplary implementation, the circuitry and techniques estimate thethickness or change in thickness of a battery based on a fade or changein, loss or reduction of a capacity of the battery over time (forexample, the amount of capacity during use, operation and charging orrecharging). Here, the circuitry and techniques may determine a fade orchange in, loss or reduction of a capacity of the battery and correlatethat information to thickness or change in thickness of a battery.Notably, the fade or change in, loss or reduction of a capacity of thebattery may be estimated using any technique or circuitry now known orlater developed including, for example, based on a state of health (SOH)of the battery or a charge-voltage to charge-capacity relationship(wherein the charge voltage changes indicating a higher voltage valuefor the same amount of charge stored within the battery which correlatesto a capacity fade of the battery).

With reference to FIGS. 2A, 2B, 3 and 4, in one implementation, system10 estimates a fade or a change in or loss or reduction of a capacity ofthe battery over time (for example, the amount of capacity during use,operation and charging or recharging). Using that information, system 10may estimate a thickness or change in thickness of the battery. See, forexample, FIGS. 3 and 4. FIG. 3 shows an illustration of an exemplaryrelationship of the thickness of the battery/cell as a function ofcapacity (or lost capacity). Here, the battery/cell thickness increasesas a function of capacity fade, or capacity retention plotted in reverseorder. In other words, there is an increase in thickness in relation toan amount of capacity lost via use or over time. FIG. 4 shows anillustration of an exemplary relationship of the maximum thickness of acell as a function of the number of cycles achieved before the cell'scapacity reached 80% of the initial capacity. Notably, adaptive chargingextended the cycle life of the cells by mitigating the degradationmechanisms taking place while the cells were constantly charging anddischarging. Notably, the thickness or swell measurements were madeusing a static measurement technique. Measurements were made in 100cycle intervals until the cell reached 80% of initial capacity. Here,system 10 correlates the swell of the battery to the percentage ofcapacity retention.

Notably, the relationship between the swell of the battery and the fadeor reduction of capacity of the battery may be estimated using anytechnique now known or later developed—all of which are intended to fallwithin the scope of the present disclosures. In various applications,there is a high correlation between swelling and reduction of capacity.In one implementation, the relationship or correlation is determinedusing empirical data, test data, characterization/simulation data,theoretical data or a mathematical relationship. For example,determining a relationship between a change in terminal voltage (overcharge-discharge cycling) and the capacity retention (while alsomeasuring, detecting or determining a swell of the battery) may beemployed to correlate a swell of the battery to the capacity retention.

Such relationship may be developed, acquired or determined using staticor dynamic configurations or techniques wherein acquired empirical datais collected when the battery is connected to a test platform, in situ,when the battery is in use, and/or when the battery is undergoingcharging. All such environments or techniques are intended to fallwithin the scope of the present disclosures.

In one implementation, one or more related batteries are characterizedby cycling (charging/discharging in conjunction with acquisition ofswelling measurements) the one or more related batteries to correlatecapacity fade of each battery with a thickness or change in thickness ofthe battery. The empirical correlation data may then be manipulated (forexample, averaged) to provide a correlation of capacity retention to theswell for like, similar or related batteries (for example, a certainrelated series, manufacturing lot, chemistry, architecture and/ordesign). For example, in one exemplary implementation, the data ortables are generated to correlate the changes in terminal voltage withthe SOH of the battery as well as the thickness or changes in thicknessof the battery. Different charging sequences or parameters may be usedfor different batteries to create more complete correlationrelationships between changes in terminal voltage values, capacity fadeand thickness or changes in thickness of the batteries. Notably, thechanges in terminal voltage values, capacity fade and thickness of thebattery may also be correlated using physical models related to thetransport of lithium-ions within the battery.

The aforementioned correlation or relationships may be stored in memory(for example, in a database or look-up table) during manufacture, testor calibration and accessible to the circuitry or processes of thepresent disclosures during operation (for example, via access of thememory). The memory may be integrated or embedded in other circuitry(for example, control or processing circuitry associated with thebattery) or discrete. The memory may be of any kind or type (forexample, EEPROM, Flash, DRAM or SRAM).

Further, the memory may be a permanent, semi-permanent or temporary(i.e., until re-programmed) storage. As such, in one implementation, thememory may be one time programmable, or data, equations, relationships,and/or look-up table employed by the control/processing circuitry may beone time programmable (for example, programmed during test or atmanufacture). In another implementation, the memory is more than onetime programmable and, as such, the predetermined ranges or valuesemployed by the control circuitry may be modified after test and/ormanufacture.

In operation, in one implementation, processing circuitry accesses thecapacity fade or conversely the capacity retention to swellrelationship, for example, as a mathematical function or values in alook-up table. The processing circuit can use a measurement related tothe capacity retention of a battery and the capacity retention to swellrelationship to estimate the thickness or change in thickness of thebattery.

The data corresponding to the swell of the battery, in relation tocapacity fade of the battery, may be acquired using any technique nowknown or later developed. For example, the swell data may be acquiredusing a static environment or configuration (whereby the battery iselectrically disconnected from the charging circuitry) or a dynamicenvironment or configuration (whereby the battery is electricallyconnected to the charging circuitry—and the battery may be undergoingcharging or discharging). In both instances, data is acquired to developa relationship between or the correlation of the swell of the battery tothe fade of a capacity of the battery over time. In one implementation,the empirical data (which may consist of data from one or morebatteries) provides for a relationship or correlation for related seriesof batteries, related manufacturing lots of such batteries, or relatedchemistries, architectures or designs of such batteries. Notably, theempirical data may be employed in generating a mathematical relationshipwhich is representative of the correlation of the swell of the batteryto the fade of a capacity of the battery.

In one particular exemplary implementation of a static environment orconfiguration employed to measure, determine or detect swelling, thebattery, upon termination of charging cycle(s), is electricallydisconnected from charging circuitry and thickness or swell related datais acquired. Here, the battery is electrically disconnected fromcharging circuitry to control, manage or reduce measurement error(s)from relaxation of battery thickness when the battery is at “rest” orstable. (See, for example, FIG. 5). In one exemplary implementation,thickness measurements are acquired within minutes (for example, withinless than ten minutes) of electrically disconnecting the battery fromthe charging circuitry—for example, using a thickness gaugeinstrument/tool (such as, Mitutoyo Digimatic Indicator).

With specific reference to FIG. 5, in one exemplary implementation, anarray of measurements may be taken on a grid of points (for example,fixed points with a particular spacing (for example, 5 mm spacing) onthe external surface of the battery; notably, theconfiguration/arrangement of measurement points as an array isexemplary, any configuration/arrangement may be employed). It may beadvantageous to define the measurement locations in order to ensure thatcell thickness measurements are made consistently at the same pointsalong the surface. In this implementation, thickness measurements ateach measurement location are recorded in a specified order (forexample, each row from left to right starting with the row closest toone of the electrode tabs). In one implementation, the point on theexternal surface of the battery representing the maximum thickness maybe used to calculate swelling—for example, as a percentage of originalthickness at the present cycle relative to the very first cycle. Thelocation of the maximum thickness of the cell may vary from cycle tocycle since swelling may exhibit a non-uniform pattern in which case,the measurement location of maximum swelling may change. The array ofmeasurements may be employed, via control and processing circuitry, toconstruct surface plots of the cell which track the evolution in cellthickness with cycling and pinpoint areas of the cell where the largestamount of swelling takes place.

It should be noted that the aforementioned implementations may beimplemented in a dynamic environment or configuration whereby thicknessor swelling data is obtained while the battery is or remainselectrically connected to the charging circuitry and, in oneimplementation, during charging and/or discharging cycles. Suchthickness or swelling measurements are preferably made without anyweight(s) disposed on the battery in order to identify the thickestpoints of the external surface of the battery.

The present disclosures may employ non-contact techniques orconfigurations to measure, determine or detect swelling. Here, thenon-contact techniques or configurations (for example, inductive orcapacitive sensing) are employed to acquire data corresponding to theswell of the battery, in relation to fade or a change in or loss orreduction of a capacity of the battery. (See, for example, FIGS. 6A and6B). The non-contact techniques or configurations may be implemented ina static or dynamic environment. For example, in one implementation, oneor more inductive or capacitive sensors is/are disposed or locatedproximate to or on an external surface of the battery to measureswelling related data, for example, in real-time as the batteryundergoes charging or discharging (i.e., is cycled). (See, for example,FIGS. 6C and 6D wherein a plurality of coils or plates is located ordisposed in or on a surface (for example, planar or parallel surface)that is proximate and opposing to the surface of the battery (see FIG.6C wherein the surface of the substrate in which theinductive/capacitive sensors are disposed is located a distance “D” fromthe external surface of the battery) or is integrated in or on thesurface of the battery (see FIG. 6D) when, for example, the externalsurface of the battery is non-metallic).

With continued reference to FIG. 6C, the coils or plates are configuredrelative to the surface of the battery to acquire data which isrepresentative of the thickness or change in thickness (or rate ofchange) of the battery; notably, the coil/plate array configurationillustrated in FIGS. 6C and 6D is exemplary, any inductive coil orcapacitive plate arrangement may be employed (including, in oneimplementation, both coil(s) and plate(s)). In one implementation,electronic circuitry measures the change in inductive/capacitivecoupling between one or more coils/plates and the surface of the batteryto measure the displacement of the surface of the battery (andconsequently, swelling). Notably, although a plurality of coils/platesare illustrated and described, the present disclosures may beimplemented using one inductive coil or capacitive plate.

The non-contact (inductive or capacitive) thickness measurements may beintermittently, periodically or continuously acquired (for example,periodically in the range of seconds (for example, between 1 to 30seconds—for example, at 16 second intervals). This measurement techniquemay provide finer level of granularity (relative to the contacttechniques/configurations); indeed, such techniques/configurationsfacilitate or allow acquisition of data corresponding to batterythickness or changes in the thickness during charge or discharge cyclesor operations. Notably, the non-contact techniques or configurations maybe implemented in battery test platforms as well as when the battery isincorporated into the actual electronic device/product (i.e., the devicein which the battery is mounted in and is intended to power).

In one particular implementation, in the context of inductive sensing, acurrent carrying coil in proximity to a metal surface will induce eddycurrents that in turn generate a magnetic field that opposes theoriginal field of the coil. The size of the field generated is afunction of the target surface distance and the target composition. Ifthe coil is incorporated as part of a resonator, with the addition of aparallel capacitor, then it can be shown that the power supplied is thesum of the eddy current and inductor losses. Measurements of theequivalent parallel impedance and the oscillation frequency and therebyinductance of the resonant circuit can be made and the inductance Lcalculated as L=1/[C*(2πf)²]. (See, for example, FIG. 6A).

Notably, with reference to FIG. 6C, in those instances where theexternal surface of the battery includes or consists of a polymer orlike material/coating thereon (for example, a material/coating thatadversely impacts inductive/capacitive sensing), it may be advantageousto include a target material (for example, copper film/foil such asapproximately 20-40 micron copper pliable film/foil) on the externalsurface of the battery which opposes the sensor substrate. Such aconfiguration may improve the accuracy of the displacement measurements(and consequently, swelling measurements).

In one exemplary implementation, the swelling measurement system mayemploy a inductive measurement circuitry (for example, Texas InstrumentsLDC 1000 inductance-to-digital converter device), an array of analogmultiplexer chips and an array of printed circuit board coils todetermine the relative distance between the sensing coil and thebattery. A control circuitry (for example, a microcontroller) mayimplement one or more of the following operations: (a) obtain thedigital proximity data from the inductive chip; (b) apply averaging,min, max, functions to the data; (c) apply corrections based ontemperatures or other factors; (d) convert relative proximity data toabsolute proximity data using a look-up-table; (e) manage which coilsare being used by controlling the multiplexers; (f) implement the userinterface or (g) transmit the data to the data collection system.

Further, in one exemplary implementation of a test platform, aninductive sensor coil and supporting circuitry are connected to acommunication port (for example, a USB hub) that in turn is attached toa circuit board. The coil is suspended in a fixed plane above thecircuit board, allowing for insertion of a battery between the coil andboard. A calibration curve and associated formula allow the conversionof inductance to equivalent thickness. The target battery may beinserted into the measurement cavity between the coil and board andconnected to a battery cycling board. The battery cycling board storesand executes a charging and discharging protocol specific to the batterycell. The inductive sensor concurrently measures inductance andeffective parallel impedance at a set frequency and stores thisinformation in a separate data file (which may also include a timestamp).

In another exemplary implementation, the thickness or change inthickness of a battery is estimated based on a SOH of the battery. Asnoted above, the SOH of a rechargeable battery (for example, arechargeable lithium-ion battery) is a parameter that describes,characterizes or is representative of the “age” of the battery, thedegradation levels of the battery or an ability of the battery to holdcharge, for example, relative to a given time in operation (for example,the initial time in operation).

With reference to FIGS. 2A, 2B, 3 and 4, in one implementation, system10 estimates a SOH of the battery and, using that information, system 10may estimate a thickness or change in thickness of the battery. In thisimplementation, system 10 correlates the swell of the battery to the SOHof the battery. Thus, in operation, processing circuitry accesses a SOHto swell correlation/relationship, for example, as data in a look-uptable or as a mathematical relationship, to estimate the thickness orchange in thickness of the battery based on or using a SOH of thebattery. As noted above, the SOH of the battery deteriorates as thebattery “ages” (for example, undergoes cycling). (See, for example, FIG.7).

The relationship between or the correlation of the swell of the batteryto the SOH of the battery may be estimated using any technique now knownor later developed—all of which are intended to fall within the scope ofthe present disclosures. In addition, such relationship or correlationmay employ the same or similar techniques and circuitry described abovein connection with determining or developing a relationship orcorrelation between thickness or change in thickness of the battery tothe capacity retention of the battery. For example, in oneimplementation, the relationship or correlation of the swell of thebattery to the SOH of the battery is determined using empirical data,test data, characterization/simulation data, theoretical data or amathematical relationship. For example, determining a relationshipbetween a change in terminal voltage (over charge-discharge/use cycling)to the SOH of the battery (while measuring, detecting or determining aswell of the battery) may be employed to correlate a swell of thebattery to the capacity retention. In one implementation, one or morerelated batteries are characterized by cycling (charging/discharging inconjunction with acquisition of swelling measurements) such batteries tocorrelate SOH of each battery with a thickness or change in thickness ofthe battery. The empirical correlation data may then be manipulated (forexample, averaged) to provide a correlation of capacity retention to theswell for like, similar or related batteries (for example, a certainrelated series, manufacturing lot, chemistry, architecture and/ordesign).

In another implementation, various charging techniques are used to cyclebatteries, and correlation data or tables are generated to correlate thechanges in terminal voltage with the capacity fade of thecells/batteries as well as the thickness or changes in thickness of thebatteries. Different charging techniques may be used on differentbatteries to create more extensive correlation or relationship betweenchanges in terminal voltage values, SOH and thickness or changes inthickness of the batteries. Notably, the changes in terminal voltagevalues, SOH and thickness of the battery may also be correlated usingphysical models related to the transport of lithium-ions within thebattery.

Like that described above, the correlation or relationships may bestored in memory (for example, in a database or look-up table) duringmanufacture, test or calibration, and accessible to the circuitry orprocesses of the present disclosures during operation. The memory may beintegrated or embedded in other circuitry (for example, control orprocessing circuitry associated with the battery) or discrete. Thememory may be of any kind or type (for example, EEPROM, Flash or SRAM).

In operation, in one implementation, processing circuitry accesses theSOH to battery thickness/swell relationship or correlation, for example,as data in a look-up table or as a mathematical relationship in order toestimate the thickness or change in thickness of the battery based on orusing a SOH of the battery.

The data corresponding to the swell of the battery, in relation to SOHof the battery may be same or similar techniques and circuitry describedabove in connection with determining or developing a relationship of orcorrelation between thickness or change in thickness of the battery tothe capacity retention of the battery. For example, the swell data maybe acquired using a static environment or configuration (whereby thebattery is electrically disconnected from the charging circuitry) or adynamic environment or configuration (whereby the battery iselectrically connected to the charging circuitry—and the battery may beundergoing charging or discharging). In both instances, data is acquiredto develop a relationship between or the correlation of the swell of thebattery to the SOH of the battery. In one implementation, the empiricaldata (which may consist of data from one or more batteries) provides fora relationship or correlation for related series of batteries, relatedmanufacturing lots of such batteries, or related chemistries,architectures or designs of such batteries. Notably, the empirical datamay be employed in generating a mathematical relationship which isrepresentative of the correlation of the swell of the battery to thefade or a change in or loss or reduction of a capacity of the battery.As noted above, any technique to measure thickness or change inthickness of the battery, whether now known or later developed, isintended to fall within the scope of the present disclosures.

Managing Battery Swelling

The present disclosures, in another aspect, are directed to circuitryand techniques to adapt, change or modify the charging sequence of abattery based on or using data which is representative of the thicknessor change in thickness of the battery. In this aspect of the presentdisclosures, circuitry and techniques implement adjustments to thecharging operation to modify or adapt the charging sequence (via controlsignals to the charging circuitry) based on or using data which isrepresentative of the thickness or change in thickness of the battery.For example, in one implementation, the adaptive charging techniques orcircuitry uses or employs such swelling related data, alone or inconnection with other considerations, parameters, constraints orrequirements to change, adjust, control or vary the charging currentsignal(s), including the characteristics thereof. (See, for example,FIG. 8A-8C). Notably, such other considerations, parameters, constraintsor requirements include, for example, charge-time parameter (CTP) anoverpotential (OP) or full relaxation time (FRT) of the battery, acharge pulse voltage (CPV) or a change in CPV, a partial relaxation time(PRT) of the battery, a temperature of the battery/cell (T° _(b/c)), atemperature of the charging circuitry (T°_(cc)), a temperature of thehousing (T° _(h)), a maximum current applied to the battery duringcharging operations (I_(max)) or a maximum terminal voltage duringcharging operations (V_(max)) (see, for example, FIGS. 8A-8C); adiscussion of other parameters, constraints or requirements is providedin application Ser. No. 14/252,422, which, for the sake of brevity, willnot be repeated in detail here but is incorporated by reference in itsentirety.

In the context of a pulse current charging technique (see, e.g., FIGS.9A-9D and 10A-10P), the circuitry and techniques, in one implementation,implement, provide, change, adjust or control one or morecharacteristics of the charging signal applied to the battery (forexample, a shape of charge or discharge signal (if any), amplitudethereof, duration thereof, duty cycle thereof, rest period (if any) orsequence of charge or discharge pulses) based on or using data which isrepresentative of the thickness or change in thickness of the battery.For example, the adaptive charging technique and circuitry may measureor monitor the thickness or change (or rate of change) in thickness ofthe battery (for example, using circuitry or techniques describedherein) and, in response thereto (for example, if the thickness orchange in thickness of the battery exceeds a predetermined range orvalue (which, in one exemplary implementation, is 1-10% relative to agiven cycle (for example, an initial cycle of a “new” battery), or inanother implementation, 2-8%, or is greater than or equal to 3% or 4%,or in a more preferred implementation is greater than or equal to 5%)for a given number of cycles or at a given SOH), adapt, change or modifythe charging sequence or operation (for example, reduce the peak currentapplied to the battery) to manage or control the swelling of thebattery. Here, the circuitry and techniques, based on or using datawhich is representative of the thickness or change in thickness (or rateof change in thickness wherein a predetermined range or value, in oneexemplary implementation, is less than 4%, in another implementation isless than 3%, in a preferred implementation is less than 2%, and in amore preferred implementation is less than 1%) of the battery, mayadapt, change or adjust one or more characteristics of the chargingsequence or operation—for example, reduce the amplitude of the chargepulse (including, for example, terminating the charging sequence),reduce the pulse width, introduce or apply one or more negative pulses,or increase the amplitude or pulse width of the negative pulses (in theevent that the sequence includes one or more negative pulses), increasethe duration or timing of a rest period after the pulse (in the eventthat the sequence includes one or more rest periods).

Similarly, in the context of a constant-current, constant-voltage(“CCCV”) charging technique or a step charging technique (see, e.g.,FIGS. 11A and 11B), in one exemplary implementation, the circuitry andtechniques adapt, change, adjust or control the charging operation inaccordance with swelling-related data in the event that the thickness orchange (or rate of change) in thickness of the battery exceeds apredetermined range or value. In this way, the circuitry determines,changes, adjusts or controls one or more characteristics of the chargingsignal of a CCCV charging technique or a step charging technique (forexample, in the amplitude of the current, the number of steps, to manageor control the thickness or change (or rate of change) in thickness ofthe battery during the charging operation. For example, in the eventthat the swelling of the battery exceeds a predetermined range or value,the control circuitry and techniques may reduce the amplitude of thecurrent (including, for example, terminating the charging sequence),increase the number of steps over the charge period, adjust the stepwidth of one or more of the steps, apply or introduce one or morenegative pulses into the sequence, or adjust the amplitude or pulsewidth of one or more negative pulses (i.e., in the event that the CCCVor step charge sequence includes one or more negative pulses). Further,when employing a CCCV charging operation or sequence, the transitionfrom CC to CV may be adjusted or based on the amount of swellingexperienced by a battery during, for example, the charging operation.

Notably, in addition to adaptively charging based on whether thethickness or change (or rate of change) in thickness of the batteryexceeds a predetermined range or value, such adaptive techniques mayalso be employed to control or manage the thickness or change (or rateof change) in thickness of the battery so that the battery does notexceed a predetermined range or value. The same technique may be appliedin that context. For the sake of brevity, such discussion will not berepeated.

The aforementioned predetermined ranges or values may be stored inmemory (for example, in a database or look-up table) during manufacture,test or calibration and accessible to the circuitry or processes duringoperation (for example, via access of the memory). The memory may beintegrated or embedded in other circuitry (for example, control orprocessing circuitry associated with the battery) or discrete. Further,the memory may be a permanent, semi-permanent or temporary (i.e., untilre-programmed). Indeed, in one implementation, the memory may be onetime programmable, or data, equations, relationships, or look-up tableemployed by the control/processing circuitry may be one timeprogrammable (for example, programmed during test or at manufacture). Inanother implementation, the memory is more than one time programmableand, as such, the predetermined ranges or values employed by the controlcircuitry may be modified after test or manufacture. The memory may beof any kind or type (for example, EEPROM, Flash, DRAM or SRAM).

In addition to adaptively charging based on the thickness or change (orrate of change) in thickness of the battery, or in lieu thereof, in oneimplementation, such techniques and circuitry may facilitate meeting orcompliance with safety considerations, conditions or “goals” defined by,associated with or corresponding to the battery—for example, managing orcontrolling SOC of the battery so that the thickness of the battery (orchange therein) does not exceed a predetermined range or value (whichmay depend on the SOH of the battery). In one implementation, the amountof swell is controlled or limited by adjusting the charging signal (asindicated above) or reducing the maximum SOC or the charge level of thebattery as a result of a full or complete charging sequence. Forexample, the thickness of the battery (or change in thickness of thebattery) may be limited, controlled or managed by terminating a chargingsequence when a SOC of the battery is less than 100% —for example,terminating the charging sequence when the SOC of the battery is, forexample, 85% of a previous SOC, rating or the SOC of new battery. Inthis way, the thickness or change in thickness of the battery may belimited or controlled to not exceed a given amount or change.

As indicated above, the SOC of a battery, for example, a lithium-ionrechargeable battery, is a parameter that is representative or indicatesthe level of electrical charge available in the battery. It may becharacterized as a percentage of the nominal full charge rating of thebattery, wherein a 100% SOC indicates that a battery is fully chargedand a 0% indicates that the battery is fully discharged. The SOC of thebattery may also be characterized as an available charge stored in thebattery relative to a maximum available charge stored in thebattery—wherein the maximum available charge may change over time as,for example, the battery ages or deteriorates.

In yet another implementation, the circuitry and techniques of thepresent disclosures adaptively charge a battery to an SOC by correlatinga capacity retention to an “acceptable” percentage of swelling and, inresponse charge the battery to a SOC that is defined by or associatedwith such fade or change in, loss or reduction of a capacity of thebattery. In this way, the thickness or change in thickness (or ratethereof) of the battery is managed or controlled to not exceed apredetermined range or value (for example, to reduce potentially adverseimpact or consequences of swelling) by correlating fade related data toa SOC of the battery that controls, limits or maintains the thickness orchange in thickness (or rate thereof) of the battery to a predeterminedrange or value (or not exceed a predetermined range or value).

There are many disclosures described and illustrated herein. Whilecertain implementations, features, attributes and advantages of thedisclosures have been described and illustrated, it should be understoodthat many others, as well as different or similar implementations,features, attributes and advantages of the present disclosures, areapparent from the description and illustrations. As such, theimplementations, features, attributes and advantages of the disclosuresdescribed and illustrated herein are not exhaustive and it should beunderstood that such other, similar, as well as different,implementations, features, attributes and advantages of the presentdisclosures are within the scope of the present disclosures.

Indeed, the present disclosures are neither limited to any single aspectnor implementation thereof, nor to any combinations or permutations ofsuch aspects or implementations. Moreover, each of the aspects of thepresent disclosures, or implementations thereof, may be employed aloneor in combination with one or more of the other aspects of the presentdisclosures or implementations thereof.

With reference to FIGS. 12A-12C, it should be noted that the circuitryof the present disclosures may include or employ the control/processingcircuitry, monitoring circuitry or charging circuitry described andillustrated in PCT Application Serial No. PCT/US2012/30618, U.S.application Ser. No. 13/366,352, U.S. application Ser. No. 13/626,605,U.S. application Ser. No. 13/657,841, U.S. application Ser. No.13/747,914, all of which are incorporated herein by reference. For thesake of brevity, the discussion regarding such circuitry, in the contextof the techniques of the present disclosures, will not be repeated.

As noted above, the present disclosures may employ any technique orcircuitry now known or later developed to estimate SOH of a battery orthe impact of SOH on the relationship between a terminal voltage andcharge capacity, which may be employed to determine the thickness orchange in thickness of the battery. For example, the SOH of the batterymay be calculated or estimated using the techniques set forth in, forexample, PCT App. Serial No. PCT/US2012/30618 and U.S. application Ser.Nos. 13/366,352 and 13/657,841.

Notably, “circuitry”, means, among other things, a circuit (whetherintegrated or otherwise), a group of such circuits, one or moreprocessors, one or more state machines, one or more processorsimplementing software, one or more gate arrays, programmable gate arraysor field programmable gate arrays, or a combination of one or morecircuits (whether integrated or otherwise), one or more state machines,one or more processors, one or more processors implementing software,one or more gate arrays, programmable gate arrays or field programmablegate arrays. The term “data” means, among other things, a current orvoltage signal(s) (plural or singular) whether in an analog or a digitalform.

Further, control/processing circuitry (employed to implement theoperations or techniques described herein) may perform or execute one ormore applications, routines, programs or data structures that implementparticular methods, techniques, tasks or operations described andillustrated herein. The functionality of the applications, routines orprograms may be combined or distributed. In addition, the applications,routines or programs may be implemented by the control circuitry usingany programming language whether now known or later developed,including, for example, assembly, FORTRAN, C, C++, and BASIC, whethercompiled or uncompiled code; all of which are intended to fall withinthe scope of the present disclosures.

Moreover, monitoring circuitry and control/processing circuitry (whichis employed to implement the operations or techniques described herein)may share circuitry with each other as well as with other elements.Moreover, such circuitry may be distributed among a plurality ofintegrated circuits which may also perform one or more other operations,which may be separate and distinct from that described herein.

It should be further noted that the various circuits and circuitrydisclosed herein may be described using computer aided design tools andexpressed (or represented), as data or instructions embodied in variouscomputer-readable media, in terms of their behavioral, registertransfer, logic component, transistor, layout geometries, or othercharacteristics. Formats of files and other objects in which suchcircuit expressions may be implemented include, but are not limited to,formats supporting behavioral languages such as C, Verilog, and HLDL,formats supporting register level description languages like RTL, andformats supporting geometry description languages such as GDSII, GDSIII,GDSIV, CIF, MEBES and any other formats or languages now known or laterdeveloped. Computer-readable media in which such formatted data orinstructions may be embodied include, but are not limited to,non-volatile storage media in various forms (e.g., optical, magnetic orsemiconductor storage media) and carrier waves that may be used totransfer such formatted data or instructions through wireless, optical,or wired signaling media or any combination thereof. Examples oftransfers of such formatted data or instructions by carrier wavesinclude, but are not limited to, transfers (uploads, downloads, e-mail,etc.) over the Internet or other computer networks via one or more datatransfer protocols (e.g., HTTP, FTP, SMTP, etc.).

Indeed, when received within a computer system via one or morecomputer-readable media, such data or instruction-based expressions ofthe above described circuits may be processed by a processing entity(e.g., one or more processors) within the computer system in conjunctionwith execution of one or more other computer programs including, withoutlimitation, net-list generation programs, place and route programs andthe like, to generate a representation or image of a physicalmanifestation of such circuits. Such representation or image maythereafter be used in device fabrication, for example, by enablinggeneration of one or more masks that are used to form various componentsof the circuits in a device fabrication process.

Moreover, the various circuits and circuitry, as well as techniques,disclosed herein may be represented via simulations using computer aideddesign or testing tools. The simulation of the charging circuitry,control circuitry or monitoring circuitry, or techniques implementedthereby, may be implemented by a computer system wherein characteristicsand operations of such circuitry, and techniques implemented thereby,are imitated, replicated or predicted via a computer system. The presentdisclosures are also directed to such simulations of the inventivecharging circuitry, control circuitry or monitoring circuitry, ortechniques implemented thereby, and, as such, are intended to fallwithin the scope of the present disclosures. The computer-readable mediacorresponding to such simulations or testing tools are also intended tofall within the scope of the present disclosures.

The present disclosure may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedimplementations are to be considered in all respects only asillustrative and not restrictive. The scope of the disclosure is,therefore, indicated by the appended claims rather than by the foregoingdescription. All changes which come within the meaning and range ofequivalency of the claims are to be embraced within their scope

1. A method for estimating swelling of a rechargeable battery, themethod comprising: determining capacity fade of the rechargeable batteryin use; and estimating swelling of the rechargeable battery using thedetermined capacity fade of the rechargeable battery.
 2. The method ofclaim 1, wherein estimating the swelling comprises applying arelationship for predicting battery swelling from battery capacity fadethat was obtained by: (i) charging and discharging one or more samplerechargeable batteries for one or more charge cycles; (ii) measuringcapacity fade of the one or more sample rechargeable batteries; (iii)measuring swelling of the one or more sample rechargeable batteries;(iv) repeating (i)-(iii) one or more times, thereby obtaining two ormore data points corresponding to capacity fade and swelling in two ormore charge cycles for the one or more sample rechargeable batteries;and (v) forming the relationship for predicting battery swelling frombattery capacity fade using the two or more data points.
 3. The methodof claim 2, further comprising: storing the relationship in a memory;and retrieving the relationship from memory for estimating the swelling.4. The method of claim 1, wherein determining capacity fade of arechargeable battery comprises determining capacity fade in two or morecharge cycles.
 5. The method of claim 1, further comprising adjusting acharging sequence for the rechargeable battery based at least in part onthe estimated swelling of the rechargeable battery.
 6. The method ofclaim 5, wherein adjusting the charging sequence reduces the estimatedswelling of the rechargeable battery.
 7. The method of claim 5, whereinadjusting the charging sequence is selected from operations consistingof: reducing an amplitude of a charge pulse, terminating the chargingsequence, reducing the pulse width, applying one or more negativepulses, increasing an amplitude of a negative pulse, increasing a widthof a negative pulse, increasing a duration of a rest period, changing atiming of a rest period, and any combinations thereof.
 8. The method ofclaim 5, wherein adjusting the charging sequence comprises adjusting oneor more aspects of the charging sequence comprises adjusting one or moreaspects of a charge or discharge pulse selected from the groupconsisting of: a shape of the pulse, an amplitude of the pulse, aduration of the pulse, a duty cycle a sequence of pulses, and a restperiod between the pulses.
 9. The method of claim 5, wherein adjustingthe charging sequence comprises adjusting one or more characteristics ofa charging signal of a constant-current, constant-voltage (CCCV)charging technique or a step charging technique.
 10. The method of claim9, wherein adjusting the charging sequence comprises adjusting anamplitude of a charge current or a number of steps of charge current.11. The method of claim 9, wherein adjusting the charging sequencecomprises determining that the swelling of the battery exceeds apredetermined range or value; and reducing an amplitude of a chargecurrent, terminating the charging sequence, increasing a number ofcharge steps over a charge period, adjusting a step width of one or morecharge steps, introducing one or more negative pulses, or adjusting anamplitude or pulse width of one or more negative pulses.
 12. The methodof claim 5, wherein adjusting the charging sequence comprisesterminating a charging sequence when the SOC of the battery reaches 85%or lower of a previous or initial SOC of the battery.
 13. The method ofclaim 5, wherein adjusting the charging sequence is at least partiallybased on a parameter selected from the group consisting of: anover-potential (OP) of the battery, a full relaxation time (FRT) of thebattery, a charge pulse voltage (CPV), a change in CPV, a partialrelaxation time (PRT) of the battery, a temperature of the battery/cell(T° _(b/c)), a temperature of the charging circuitry (T°_(cc)), atemperature of the housing (T° _(h)), a maximum current applied to thebattery during charging operations (I_(max)), and a maximum terminalvoltage during charging operations (V_(max))
 14. A method fordetermining a relationship for predicting swelling of batteries fromcapacity fade of the batteries, comprising: (a) charging and dischargingone or more rechargeable batteries for one or more charge cycles; (b)measuring capacity fade of the one or more rechargeable batteries; (c)measuring swelling of the one or more rechargeable batteries; (d)repeating (a)-(c) one or more times, thereby obtaining two or more datapoints corresponding to capacity fade and swelling in two or more chargecycles for the one or more rechargeable batteries; (e) determining therelationship for predicting battery swelling from battery capacity fadeusing the two or more data points; and (f) storing data describing therelationship in a memory. 15-18. (canceled)
 19. A method for estimatingswelling of a rechargeable battery, the method comprising: measuring achange of inductance or capacitance between one or more inductive orcapacitive sensors and a surface of the battery or a metallic componentof the battery; and calculating a displacement of said surface or saidmetallic component from the change of inductance or capacitance, andestimating swelling of the battery from the displacement.
 20. The methodof claim 19, wherein measuring the change of inductance or capacitancecomprises inducing eddy currents to generate an eddy-current magneticfield.
 21. The method of claim 20, wherein the one or more inductive orcapacitive sensors comprise one or more inductive sensors that eachcomprises a coil to carry a current to induce eddy currents to generatean eddy-current magnetic field.
 22. (canceled)
 23. A system forestimating swelling of a rechargeable battery, the system comprising:(a) charging circuitry configured to apply a charging sequence for therechargeable battery; (b) measurement circuitry configured to measurevoltage or charge passing at terminals of the rechargeable battery; and(c) logic configured to: determine capacity fade of the rechargeablebattery in use, wherein the logic determines capacity fade usingmeasured voltage and/or charge from the measurement circuitry; andestimate swelling of the rechargeable battery using the determinedcapacity fade of the rechargeable battery.
 24. The system of claim 23,wherein estimating the swelling comprises applying the determinedcapacity fade to a relationship for predicting battery swelling frombattery capacity fade.
 25. The system of claim 23, wherein the logic isfurther configured to adjust the charging sequence, applied by thecharging circuitry, based at least in part on the estimated swelling ofthe rechargeable battery.
 26. The system of claim 23, wherein the logicis further configured to obtain the relationship for predicting batteryswelling from battery capacity fade.
 27. The system of claim 23, whereinthe logic is further configured to adjust a charging sequence for therechargeable battery based at least in part on the estimated swelling ofthe rechargeable battery.
 28. A system for estimating swelling ofbatteries, the system comprising: one or more inductive or capacitivesensors disposed proximate to a surface of a battery or integrated in oron a non-metallic surface above a metallic component of the battery; andan electronic circuitry configured to: obtain proximity data indicatinga change of inductive and/or capacitive coupling between the one or moresensors and said surface or said metallic component; and calculate adisplacement of said surface or said metallic component from theproximity data, thereby estimate swelling of the battery.
 29. The systemof claim 28, wherein the one or more sensors comprise one or moreinductive sensors that each comprises a coil to carry a current toinduce eddy currents to generate an eddy-current magnetic field. 30-35.(canceled)
 36. A method for determining a relationship for predictingswelling of batteries from a state of health (SOH) of the batteries,comprising: (a) charging and discharging one or more rechargeablebatteries for one or more charge cycles; (b) measuring values of the SOHof the one or more rechargeable batteries; (c) measuring swelling of theone or more rechargeable batteries; (d) repeating (a)-(c) one or moretimes, thereby obtaining two or more data points corresponding to theSOH and swelling in two or more charge cycles for the one or morerechargeable batteries; (e) determining the relationship for predictingbattery swelling from the SOH using the two or more data points; and (f)storing data describing the relationship in a memory. 37-40. (canceled)